Lower heap size limits on systems that are short of virtual memory.

src/heap.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 134 matching lines @@
       last_idle_notification_gc_count_init_(false),
       configured_(false),
       is_safe_to_read_maps_(true) {
   // Allow build-time customization of the max semispace size. Building
   // V8 with snapshots and a non-default max semispace size is much
   // easier if you can define it as part of the build environment.
 #if defined(V8_MAX_SEMISPACE_SIZE)
   max_semispace_size_ = reserved_semispace_size_ = V8_MAX_SEMISPACE_SIZE;
 #endif
 
+  intptr_t max_virtual = OS::MaxVirtualMemory();
+
+  if (max_virtual > 0) {
+    // If we have limits on the amount of virtual memory we can use then we may
+    // be forced to lower the allocation limits.  We reserve one quarter of the
+    // memory for young space and off-heap data.  The rest is distributed as
+    // described below.
+    if (code_range_size_ > 0) {

[Kasper Lund, 2011/06/01 08:46:04]

Maybe introduce two local variables, half and quarter, and use them instead of
the repeated max_virtual >> {1,2}.

+      // Reserve a quarter of the memory for the code range.  The old space
+      // heap gets the remaining half.  There is some unavoidable double
+      // counting going on here since the heap size is measured in committed
+      // virtual memory and the code range is only reserved virtual memory.
+      code_range_size_ = Min(code_range_size_, max_virtual >> 2);
+      max_old_generation_size_ =
+          Min(max_old_generation_size_, max_virtual >> 1);
+    } else {
+      // Reserve three quarters of the memory for the old space heap including
+      // the executable code.
+      max_old_generation_size_ = Min(max_old_generation_size_,
+                                     (max_virtual >> 2) + (max_virtual >> 1));
+    }
+  }
+
   memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
   global_contexts_list_ = NULL;
   mark_compact_collector_.heap_ = this;
   external_string_table_.heap_ = this;
 }
 
 
 intptr_t Heap::Capacity() {
   if (!HasBeenSetup()) return 0;
 
@@ skipping 5758 matching lines @@
 }
 
 
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 } }  // namespace v8::internal